Knee Defender is a set of rubber grips that attach to the seat-back tray in front of you. Much like the previous bottle trick uses the tray as a wedge to keep the seat from leaning too far back KneeDefender uses the same principle only with less bulk, more stability, and more room for your laptop.

According to the Knee Defender website the device doesn't fall afoul of any FAA regulations as it is only used during the flight and not during take offs and landings—when your tray table must be up and locked. Knee Defender is available directly from the manufacturer at the link be below at a cost of $14.95 per pair.

Have a clever DIY solution that is more compact than the water bottle trick and cheaper than buying Knee Defender? Let's hear about it in the comments.